The present invention relates to a new and novel process for the recycling of old asphaltic pavements into new durable asphalt pavements without the need to add new aggregate material and rejuvenating or softening agents. Furthermore, the process of the present invention is carried out at the ambient temperature without the need to heat the old asphalt pavement.
All of the methods currently employed to recycle old asphaltic pavements consist of the following essential steps. First, the old pavement must be crushed and carefully screened. This process is usually conducted at a site removed for surface being repaved. Second, a quantity of new aggregate must be heated to about 700.degree. F. and then added to and mixed with the old asphaltic pavement with the resultant mixture having a temperature of about 270.degree. F. Third, a rejuvenation agent or solvent is added to soften the old asphalt and return it to its original softness and life, i.e., penetration and ductility. Alternatively, new paving grade asphalt cement is added to the mixture. Fourth, the old asphalt, new aggregate, rejuvenation agent, or cement, must be mixed at a temperature of approximately 270.degree. F. Finaly, the hot mixture is brought to the road surface site and is laid on the road base, leveled and rolled, while still hot into a new pavement.
These conventional processes however suffer from many disadvantages. There is an immense consumption of energy for heating the new aggregate and the old asphaltic pavement. A rejuvenation material must be employed. Expensive and specially built mixing equipment is required to facilitate the addition of the heated new aggregate to the recycled material in order to avoid burning the old asphalt. These processes can only use about two-thirds of the old asphaltic pavement which means that the other one-third must be disposed. Also, new aggregate must be purchased to replace the one-third which cannot be used. These processes are usually conducted at asphalt plants far removed from the road surface site which requires transportation to and from the site. The new pavement must be laid and compacted while still hot. Finally, the resulting strength of the new road surface, i.e. the compressive strength is normally much less than a completely new hot-mix pavement.
Additionally, there are problems in meeting air pollution standards.
The process of the present invention overcomes all of these problems as it can use 100% of the old asphaltic pavement material without the need for rejuvenation and heating. This process can be done at the road surface site. In addition, and totally unexpected, is the fact that the new pavements made in accordance with the present invention have an extremely high compressive strength.